Russian Prime Minister Dmitry Medvedev has slammed the chief of the Ukrainian security service SBU, Vasily Gritsak, for claiming Russia was somehow involved in Tuesday’s terrorist bomb blasts in Brussels.

“The head of the Ukrainian SBU Gritsak, who sees a Russian connection in the Brussels terrorist attacks is a dimwit,” Medvedev wrote on his Facebook page.

Earlier, Medvedev offered deep condolences on behalf of the Russian Cabinet and on his own behalf over the heavy casualties caused by the terrorist attacks in Brussels.

“The latest events merely underscore the need for concerted action by the international community in the struggle against terrorism,” he said on his page in Facebook.

Later, he added his comment regarding Gritsak’s claims. A series of terrorist attacks hit the Belgian capital on Tuesday morning. According to the latest reports, no less than 26 people were killed. Two explosions occurred at Brussels airport, leaving at least eleven dead and dozens of others injured. Another terrorist attack was at the Maalbeek metro station, near the European District. The Brussels’s public transport operator STIB has said the metro blast killed 15 and injured 55 others.